1. Field of the Invention
The present invention relates to a circuit module including amplifying means for amplifying multiple types of signals.
2. Description of the Related Art
These days, there is an increasing demand for multiband, multimode mobile communication terminals, such as cellular phones and mobile information terminals, which support multiple communication systems of different frequency bands or different modulation methods. Therefore, on a transmission side of this type of mobile communication terminal, a circuit module that supports multiple radio frequency signals of different frequency bands is mounted, as shown in FIG. 11 (for example, see Patent Document 1). A circuit module 500 shown in FIG. 11 is a module for amplifying radio frequency signals of multiple frequency bands (Bands), and includes a transmission route R1 through which input signals RFin_BC0 (800 MHz band) and RFin_BC3 (900 MHz band) are amplified and are output as output signals RFout_BC0 (800 MHz band) and RFout_BC3 (900 MHz band) and a transmission route R2 through which an input signal RFin_BC6 (2 GHz band) is amplified and is output as an output signal RFout_BC6 (2 GHz band).
In the transmission route R1, the input signals RFin_BC0 and RFin_BC3 input into a SAW filter 501 are switched by a switch 502 and are selectively input into an input terminal of a power amplifier 503. Then, the input signals RFin_BC0 and RFin_BC3 amplified by the power amplifier 503 are input into a non-reciprocal circuit 505, which is disposed subsequent to the power amplifier 503, via a coupler 504 and are output to the exterior of the circuit module 500 via a switch 506. Accordingly, the non-reciprocal circuit 505 prevents a signal reflected by, for example, an antenna element (not shown), disposed closer to the switch 506 from being output to the coupler 504 (power amplifier 503). Part of the transmission signals RFin_BC0 and RFin_BC3 amplified by the power amplifier 503 is separated in the coupler 504 and is output to the exterior of the circuit module 500 as an output signal Coupler out.
In the transmission route R2, the transmission signal RFin_BC6 input into a SAW filter 507 is input into an input terminal of a power amplifier 508. Then, the input signal RFin_BC6 amplified by the power amplifier 508 is input into a non-reciprocal circuit 509, which is disposed subsequent to the power amplifier 508, and is output to the exterior of the circuit module 500. Accordingly, as in the above-described transmission route R1, the non-reciprocal circuit 509 prevents a signal reflected by, for example, an antenna element (not shown), disposed subsequent to the isolator 509 from being output to the power amplifier 508. Part of the transmission signal RFin_BC6 amplified by the power amplifier 508 is output to the exterior of the circuit module 500 as an output signal Coupler out via a capacitor 510 which is connected at one end between the power amplifier 508 and the non-reciprocal circuit 509.    Patent Document 1: Japanese Unexamined Patent Application Publication No. 2011-199602 (Paragraphs 0012 to 0023, FIGS. 1 and 2, and so on)